In the production of sterile packages, e.g. within the field of medicine, odontology and veterinary medicine, the object or the instrument to be sterilized is usually placed in a package, whereafter the package is closed and heated. A large problem in that connection is that the package often will burst due to the overpressure which is developed during the heating.
U.S. Pat. No. 3,088,255 discloses a method of providing a bag-like package of a flexible material, said package being adapted for use in sterilization or boiling of the contents thereof. According to this method the opening of the package is closed, after the contents have been placed within the package, by a first temporary heat sealing, wherein a filter strip for the discharge of gases developed in the package is provided in the sealing. Immediately after the heat treatment of the contents of the package a second, final sealing is provided, which completely closes the filter strip, so that a hermetical package is obtained.
A disadvantage of the method according to the above patent is that the sealing process must be performed in two steps, a temporary sealing being provided before the heat treatment and a final sealing after the heat treatment. By the final sealing air is prevented from entering into the package, if the filter strip should come loose.
Another disadvantage is that the package produced according to the known method is difficult to open.